The thrust of Vasek's research is multiscale modeling of deformation and fracture behavior of materials that links electronic, atomic, nano, and macroscopic scales. He works principally on the atomic level, which includes development of interatomic potentials that reflect both metallic and covalent aspects of bonding, as well as properties such as ferromagnetism. This modeling involves atomistic studies of dislocations and their glide modes, structure and properties of interfaces, and interactions of these extended defects with other crystal defects.